1. Field of the Invention
The invention relates to an apparatus for determining the concentration profiles of fluids, i.e. liquid or gaseous substances along a given path, in which a line is laid along the path which allows substances to penetrate into its interior. The pipe is filled with a test medium, and the column of the test medium is forced through the pipe at chronological intervals and moved past a sensor that is sensitive to the substances. A first closure is incorporated between the sensor and the line.
2. Description of the Related Art
An apparatus of that type is known from German patent specification No. 34 31 907. There, the line is formed by a hose, which is laid along a given path to be monitored, such as a pipeline. The hose is filled with air as a test medium. If there is a leak, substances reach the site of the leak in the hose, and thus make a mark in the column of the test medium. One end of the hose is provided with a valve, which separates the sensor form the hose. The other end of the hose is open. To measure the concentration profile, the valve is opened and the column of test medium is moved past the sensor. By plotting the time when the column moves past in conjunction with the sensor signal, it can be ascertained where the leak is located along the route.
The prior art apparatus has the disadvantage, however, that routes to be monitored which are excessively long are subject to error deviations. In long lines, the column of test medium is not stationary, because of the influence of air pressure fluctuations, and these lead to major measurement errors.